1. Field of Invention
This invention relates to a paper feeding apparatus, and more particularly to such apparatus using a holder table for holding pieces of paper stacked thereon and feed rollers for feeding the pieces of paper one by one to the platen of a printing device.
2. Description of the Prior Art
Usually, in the foregoing type of apparatus, the motor for driving the feed rollers also functions to rotate the platen, and a spring clutch is interposed between the motor and the feed rollers, to transmit to the feed rollers only the rotation in the paper feed direction. Moreover, for printing on a new piece of paper, the motor is rotated forwardly by a predetermined amount. This forward rotation is transmitted to the feed rollers and the platen. As a result the uppermost paper sheet on the holder table is fed to the platen side and set at a predetermined printing start position on the platen. Thereafter printing is started with depression of keys and the motor is rotated forwardly at each printing line to effect changing of lines.
The motor is sometimes rotated reversely for the purpose of correction and hence the platen is reverse-rotated, so that printing paper on the platen is fed in the direction opposite to the paper feeding direction. In this case, the reverse rotation of the motor should be cut off by the spring clutch and should not be transmitted to the feed rollers. But, in case the load, acting on the feed rollers against the reverse rotation, is small, the feed rollers may be rotated reversely. (Detailed reasons for this action will be discussed hereinafter.)
If there occurs such reverse rotation of the feed rollers, the uppermost printing paper sheet, or, as the case may be, both the uppermost sheet and the printing paper next in line, are retreated from the paper feed start position, so that the next paper feed is started from this retreated position. Therefore, the fed printing paper is set at a position before reaching the predetermined printing start position on the platen. Consequently, printing for the paper is started from a position different from the printing start position on the other printing papers, or printing may be started before the front end of the paper reaches the printing position.
In this type of paper feed apparatus, moreover, the plurality of feed rollers are rotatably supported by the frame of the apparatus. The holder table, for holding stacked paper, is also pivotally supported by the frame. The holder table is urged so that the upper surface of the uppermost sheet of paper thereon is kept in pressure contact with the feed rollers, and the paper sheets are fed one by one with rotation of the feed rollers.
The foregoing type of paper feeding apparatus, however, is disadvantageous, since the frame is formed integrally by molding and tends to become distorted at its end portions. Consequently, the pivotal axis of the holder table and the axis of rotation of the feed rollers are no longer disposed on the same plane, and are not properly aligned. Accordingly, the uppermost paper sheet on the holder table is no longer kept at constant uniform pressure contact with the feed rollers. This would tend to impede proper paper feeding operation.